Hike the Bluff - this fun little hike is great this time of year. If you time it right you can watch the sun set over the Trout Creek Valley.
Bike around Fundy National Park - the steep hills are a challenge yes, but the views and vistas are a worthwhile reward. Not to mention just think of the nice speed you'll get coasting down into Alma.
Explore the sea caves in St. Martin's - Don't just go out and say "oh yeah that's cool" Stay an entire day and see them at high tide and low tide. Have a lobster lunch, throw rocks at the waves. Maybe even take a boat tour or scramble around a bit. Enjoy them.
Have a great dessert at Adair's Wilderness Lodge - the homemade cooking there is amazing and dessert taste so much better in a wilderness setting. For you single guys this might even be a great date. Drive and dine you might say. After dessert take an evening stroll and do some star gazing. (picture from www.adairswlodge.com/gallery.html)
So there is lots to do in and around Sussex this long weekend. If you're not here you should be. If you're not out enjoying it, you should be.
Have a great long weekend all.